Method and apparatus for applying glue to cartons

ABSTRACT

An apparatus and method of sealing the flaps of fiber board cartons in which successive cartons are fed along a prescribed path over discs of tandem arranged open glue pots, the discs of one glue pot applying a relatively slow drying, cold liquid adhesive and the other applying a relatively hot fast drying thermoplastic adhesive to generally the same areas of the end flaps of each successive carton. The side flaps are then automatically folded against the end flap and held until the hot melt adhesive cools or drys sufficiently to hold the flaps together. The hot melt glue or adhesive is applied from an open heated glue pot by laterally adjustable removable discs driven through a clutch, the upper peripheries of the discs being engaged by the folded end flaps of each carton, as they pass thereover. The cartons are yieldably urged to a position to align the end flaps and into engagement with the discs by a hold down assembly which includes parallelogram suspended hold down bars which ride on opposite upper edges of the cartons. Certain discs have interrupted peripheries for applying successive spaced lengths of glue to the flaps. Thermostat controls regulate the temperature and thus the viscosity of the hot melt glue.

United States Patent [1 1 Reichert [451 Sept. 2,- 1975 1 METHOD AND APPARATUS FOR APPLYING GLUE TO CARTONS [75] Inventor: Donald G. Reichert, Tarpon Springs,

Fla.

[73] Assignee: A-B-C Packaging Machine Corporation, Tarpon Springs, Fla.

221 Filed: Aug. 21, 1973 21 Appl. No.: 390,260

[52] US. Cl. 93/36 MM; 118/202; 118/221; 118/223; 156/578 [51] Int. Cl. 831B 1/62 [58] Field of Search 93/36 MM, 36.3; 156/578; 118/202, 212, 216, 221, 222, 223, 239

Primary Examiner-Roy Lake Assistant Examiner-.lames F. Coan Attorney, Agent, or FirmNewton, Hopkins & Ormsby [5 7 ABSTRACT An apparatus and method of sealing the flaps of fiber board cartons in which successive cartons are fed along a prescribed path over discs of tandem arranged open glue pots, the discs of one glue pot applying a relatively slow drying, cold liquid adhesive and the other applying a relatively hot fast drying thermoplastic adhesive to generally the same areas of the end flaps of each successive carton. The side flaps are then automatically folded against the end flap and held until the hot melt adhesive cools or drys sufficiently to hold the flaps together. The hot melt glue or adhesive is applied from an open heated glue pot by laterally adjustable removable discs driven through a clutch, the upper peripheries of the discs being engaged by the folded end flaps of each carton, as they pass thereover. The cartons are yieldably urged to a position to align the end flaps and into engagement with the discs by a hold down assembly which includes parallelogram suspended hold down bars which ride on opposite upper edges of the cartons. Certain discs have interrupted peripheries for applying successive spaced lengths of glue to the flaps. Thermostat controls regulate the temperature and thus the viscosity of the hot melt glue.

19 Claims, 12 Drawing Figures PATENTEDSEP" ems SHEET 1 0f PATENTEDSEP 21975 SHEETHU$ FIG 5 PATENTEUSEP 21 3.. 902,406

SHEET 5 5 METHOD AND APPARATUS FOR APPLYING GLUE TO GARTONS BACKGROUND OF THE INVENTION 1. Field of the Invention Y This invention relates to an apparatus and method of sealing the flaps of cartons and is more particularly concerned with an apparatus and method .Of applying glue to the end flaps of successive righted cartons, the flaps then being folded into registry and secured in place by the glue. 1

In the prior art are the'following US. patents: US. Pat. Nos.

In US. Pat. No. 3,620,138 the broad concept of supporting and feeding successive cartons over a pair of tandem arranged glue applicators is disclosed; however, in the structure of this patent, spray nozzles and a pressurized system are used for applying the thermoplastic hot melt glue or adhesive.

The present'invention has advantages over the prior art in that no pressurized system or nozzles are employed and yet the glue is-more accurately and evenly applied and the pattern for the hot melt glue may be readily and easily changed so as to accommodate different size cartons and/or different sealing conditions while allowing the glue to be placed precisely where it is wanted. The glue is more economically applied in that less hot melt glue is required in some instances. No controls are required to regulate when the feed .of glue is to be interrupted. The number of strips of glue to be applied may be varied, as desired. There are no orifices or small openings in which dust or glue may clog. The discs of the glue pot give a visual indication of when the glue is at a proper temperature. There are no high pressure leaks The width of the strips of glue. are accurately controlled. There is proper registration between the cold glue and the hot glue strips and no overlapping of the two. The application of the glue is not appreciably effected by ambient conditions. The glue pot is self cleaning.

SUMMARY OF THE INVENTION Briefly described, the present invention includes an apparatus which passes successive righted cartons over, first a cold liquid glue. applicator, which applies spaced parallel strip of relatively cold liquid adhesive or glue to the end flaps of the carton and thenover a hot melt applicator which applies spaced parallel strips of thermoplastic hot melt glue-between the strips of cold glue. Thereafter, the apparatus closes the side flaps against the end flaps for a sufficient length of time for the hot melt glue cools and solidifies sufficiently to hold the flaps in a closed condition. The hot melt glue pot in cludes spaced removable segmented discs on a (mmon shaft, the discs having either smooth peripheries or interrupted peripheries so as to apply, selectively, a continuous strip of glue or spaced, successive, strip increments of glue. The common shaft is driven through a clutch which only rotates the shaft when the glue in the pot has been heated to an appropriate temperature such that the glue is in a liquid condition.

The hot melt glue supply tank is conveniently located on one side of the machine so that glue may be added to the tank periodically and the chilling effect of receiving the relatively cold glue, in a solid condition, does not effect the temperature of the glue in the. glue pot.

DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of an apparatus for sea]- ing the flaps of a fiber board carton, constructed in accordance with the presentinvention, the apparatus receiving successive cartons with their bottom end flaps folded to receive glue and the top flaps folded open;

FIG. 2 is a schematic side elevational view of the apparatus shown in FIG. 1, receiving a carton with its top flaps upright, the glue pots being shown in broken lines;

FIG. 3 is a schematic top plan view of the apparatus shown in FIG. 1 and 2, the cartons being removed;

FIG. 4 is an enlarged vertical sectional view taken substantially along line 4-4 in FIG. 3, parts being removed for clarity;

FIG. 5 is an enlarged vertical sectional view, taken substantially along line 5-5 in FIG. 3, parts being removed for clarity;

FIG. 6 is a view similar to FIG. 5 and showing a modified form of the hot melt glue system, showing a make up feed tank with an automatic level mechanism;

FIG. 7 is a side elevational view of a disc on the shaft of the hot melt glue pot;

FIG. 8 is an end view of the structure shown in FIG. 7;

FIG. 9 is a perspective view of a typical carton the bottom flaps of which have received the hot melt glue from discs, such as the disc depicted in FIG. 7;

FIG. 10 is a side elevational view of a modified form of disc mounted on the shaft of the hot melt glue pot; FIG. 11 is an end view of the structure shown in FIG. 10; and I i i i I FIG. l2 is a view similar to FIG. 9 but showing glue as applied utilizing the disc of FIGS. 10 and 11.

DETAILED DESCRIPTION Referring now detail to the embodiments chosen for the purpose of illustrating the present invention, numeral 20, in FIGS. 1, 2 and 3, denotes generally the frame of the apparatus for applying glue to the flaps 21 of the cartons 22 or 22a (FIG. 2) which are fed successively on the horizontal support arm or boom 23 of the machine. The machine or apparatus of the present invention is essentially the same as the apparatus disclosed in US. Pat. No. 3,620,138, except that certain modifications have been made to glue applicators so as to enable the apparatus to operate in a more suitable fashion, as pointed out hereinabove. Therefore, a more detailed description of the machine, itself is not deemed necessary.

Suffice it to state that the machine includes a pair of endless belts 24 on opposite sides of the path of travel of the cartons 22 or 220 feeds successive cartons along a longitudinal path through the frame 20. When initiallyplaced on the boom 23, the end flaps 21 of each carton 22 are folded inwardly toward each other, as depicted in FIG. 9. Furthermore, the side flaps 25 are disposed essentially vertically depending from the body of the box as depicted in. FIGS. 1 and 9. Also, the top end flaps, such as flap 26 and the side flaps 27 of each carton 22 are folded outwardly and downwardly against itself, as depicted in FIG. 1 so as to provide an upwardly opening container which, when the bottom is sealed, may receive the articles to be packed therein.

As the successive cartons 22 are urged inwardly of the frame 20, sliding on horizontal boom 23, they are engaged on opposite sides by the inner rows of the continuous belts or conveyors 24, the belts engaging the side flaps 27 of each carton 22 so as to move it longitudinally along a prescribed path denoted by the arrows 28 in FIG. 2 and the arrows 29 in FIG. 3. In the rear portion 19 of the machine, the bottom side flaps 27 are simultaneously folded inwardly against the glue on the bottom end flaps 26.

In more detail, the frame includes a pair of uprights or standards 30 which are respectively provided with a pair of opposed vertically disposed racks 31 on the forwardly and rear sides of each standard 30. The racks 31 respectively receive pinions 32 which are carried by parallel shafts 33, the shafts 33 being interconnected together for rotation in opposite directions by gears 33 which, in turn, are rotated manually by manipulation of a crank handle 34. The manipulation of crank 34 will raise or lower the hold down assembly, denoted generally by numeral 35, the pinions 32 walking upwardly or downwardly along the racks 31.

The shafts 33 are journalled by a pair of opposed guide plates 36 which carry the pins 38 which, in turn, carry slide blocks, such as slide block 39. The slide blocks 39 rides in slots 29 in standards 30.

Disposed between the parallel transversely disposed shafts 33 is a central shaft 40, having right and left hand threads which respectively threadedly engage a pair of parallel longitudinally extending support brackets 42. The support brackets 42 are both inverted channel members, through which the shafts 33 slidably project. The central shaft 40 is rotated by a manual crank 43. By manipulation of crank 43, the lateral spacing between the brackets 42 may be varied, as desired.

A plurality of pivot pins 44 project transversely through the side walls of brackets 42 and receive by their end portions a plurality of dependent or downwardly extending pendulums 45. A forward pair of pendulums 45 on one bracket 42 pivotally carry by pivot pins 48 a forward hold down bar 46 while a rear pair of pendulums 45 pivotally carry by pivot pins 48 a rear hold down bar 47.

Due to the fact that the pendulums 45 are each approximately the same length and the lower pivot pins 48 are spaced from each other by the same distance as the upper pivot pins 44 are spaced. Each hold down bar 46 or 47 is free to swing forwardly or rearwardly in arcuate paths while remaining essentially horizontally disposed.

Each of the hold down bars 46 or 47 is an angle iron, or Lshaped in cross section, so as to provide a top horizontal flange and a side vertical flange joined along a common edge to extend around the upper edge portion of a carton 22 or along the upper edge of a flap of carton 22a. The forward end portion of the hold down bars 46 is flared outwardly so as to provide upward and outward angles or guides or throat members 50 each of which diverges from the plane of the flanges of its hold down bar 46. The hold down bars 47 are provided with a similar flared guide or throat member 51.

As seen inFlG. 1, each of the four hold down members 46 and 47 are independently pivotally carried by the brackets 42, the right hand hold down members 46 and 47 being adapted to extend over the right hand upper edge of each carton 22 and the left hand held down members 46 and 47 being adapted to extend over the left hand upper edge of each container 22. Each of the hold down bars 46 and 47 are substantially identical and are of a length longer than the length of a carton 22 and are usually shorter than twice the length of a carton 22. The forward hold down bars 46 are complimentary but are individually pivotally carried while the rear hold down members 47 are likewise, opposed complimentary members.

When the carton 22 is fed along the boom 23, it is guided in its path by'the flared opposed pairs of guides 50 so that the upper edges of the cartons22 urge the bars 46 rearwardly and are received between and confined from lateral movement by the opposed hold down bars 46. The height of the brackets 42 are prearranged so that the cartons 22 or 22a receive and carry the weight of each of the hold down bars 46 as they pass therebeneath, in such a way, each carton 22 or 22a is urged against the boom 23 as the carton 22 or 22a is moved inwardly of the frame 20.

As the conveyors 24 receive each carton 22, the carton passes from beneath the forward opposed pair of hold down bars 46 to beneath the opposed pair of rear hold down bars 47, being guided by the guides 51.

By such an arrangement, the end flaps 21 of carton 22 are firmly held flat against the straight flat upper surface of the boom 23 and are disposed in a common horizontal plane, projecting inwardly toward each other, as illustrated in FIGS. 9 or 12. The hold down bars 46 and 47 also function to hold the flaps 27 in an outwardly folded condition against the body of the carton 22, as illustrated in FIG. 1. Each bar 46 or 47 weighs about 5.75 pounds but its weight may be varied from four pounds to about seven pounds.

On opposite sides of the boom 23, adjacent its innermost end, and forwardly of the conveyors 24 are a pair of opposed side guide flanges which engage the sides of each carton 22 or 22a forwardly of conveyors 24 so as to guide them along the boom 23.

HOT MELT APPLICATOR ASSEMBLY Below and outwardly of the conveyors 24, the standards 30 support a pair of opposed upstanding side panels 60, the forward ends of which are connected by a transverse panel 61. A pair of outwardly extending vertically aligned support brackets 62 project from the left hand panel 60, seen in FIG. 1, and receive, therebetween, the end portions of a tank supporting shaft 63. A pivot block 64 is pivotally carried by the shaft 63, its vertical position on shaft 63 being determined by a vertically adjustable bearing collar 65, against which the block 64 rides. The collar 65 may be adjusted axially along the length of shaft 63 so as to position the block 64. The block 64 carries the hot melt supply tank 66 of the hot melt applicator which, in turn, is provided with a removable lid or top 67. The tank 66 is electrically resistance heated, being connected to a source of electricity by cable 68. A thermostat control 69 on tank 66 determines the temperature to which the hot melt or thermoplastic glue contained within the tank 66 is heated.

As seen best in FIG. 5, the lower or discharge end of the tank 66 is provided with a vertical discharge pipe 70 which is threadedly received in a tee member 71. One end of the tee member 71 receives a plug 72 while the other, diametrically opposed, end of the tee member 71 receives a horizontally projecting stub pipe 73 which leads to a globe valve '74. The valve 74 is provided with a lever 75 which may be manipulated to open and close the valve 74.

From the valve 74, a horizontal pipe 75 leads, through a 90 elbow 76, to an upstanding pipe 77 which, in turn, is connected to the bottom portion of reservoir 86 of the glue pot 80. The pipe '75 is provided encompassed by an electrical resistance heater 79 which has a thermostatic control 82 provided with a control knob 83. By manipulation of the control knob 83, the temperature to which the pipe 75 is heated may be controlled. Upon removal of the plug 72, the pipes 73, valve 74 and pipe 75 may be cleaned out, in the event of any clogging.

As illustrated schematically in FIG. 3, the pipe 75 leads from the tank 66 to the glue pot 80 which is located centrally of the frame 20.

It will be understood that the supply tank 66 for the hot melt glue is remote from pot 80, beind disposed exterially of plate 60 on one side so that it is readily accessible and in about the same height as glue pot 80. When the glue G is in liquid condition, the horizontal level L of the glue G in the glue pot 80 will be maintained at the same or a common level L with the glue in tank 66, as illustrated in FIG. 5. Once the glue G is liquid, cold thermoplastic glue may be added to the tank 66 and melted therein without chilling the liquid glue in the glue pot 80.

A modified form of supply tank 66a, seen in FIG. 6, may be substituted for the tank 66, so as to receive an inverted bottle or jug feeder 65a, containing the thermoplastic glue in solid condition, the mouth 64a of which determines the level of the glue G in the tank 66a. In more detail, the glue tank 66a is provided with an inverted frusto-conical spout 69a which supports the inverted bottle 65a, as illustrated in FIG. 6, the spout 69a leading to a downwardly projecting pipe 70a. Pipe 70a is connected to tee member 71a having plug 72a and a discharge pipe 73a, the discharge pipe 73a leading to a valve 74a having a lever 78a. The thermostat has a control knob 83a. The valve 74a is provided with a horizontally extending pipe 75a, the end of which communicates with an elbow 76a connected to an upstanding pipe 77a leading to the glue pot 80a. Tank 66a is electrically heated, thereby heating the glue within jug 65a so that it flows into spout 69a to a level where its mouth 64a is closed. Pipe 75a is heated by heater 79a which, in turn, is controlled by thermostat 82a.

It will be understood by those skilled in the art that the pipe 75 or 75a will elongate or contract, with changes in temperature and thus the glue pot 66 or 66a, as the case may be, being pivotally mounted is free to move through a limited arc so as to compensate for the change in temperature.

Referring to FIG. 4, the glue pot 80 of the hot melt applicator includes an integrally formed pot member 81 which is a rectangular member provided with an upwardly opening central cavity. This central cavity is divided into a reservoir 86 and an applicator vat 87. The reservoir 86 is separated from the vat 87 by a removable screen partition or filter strainer 88 which is supported in its vertical transverse position by upstanding ribs 89a and 89b in the reservoir 86, upstanding ribs 90a and 90b in the applicator vat 87, and a bolt 142 on cross bar 141.

The ribs 89a and 90a are aligned, longitudinally. The

, upstanding pipe 77 or 77a, as the case may be, feeds through a port 91 in the reservoir area of the pot member 81, so as to feed the liquid glue G up between the ribs 89a and 89b. The glue G, thus passes through the port 91 and into the reservoir 86, and thence moving through the strainer 88 and into the applicator vat 87. The pot member 81 is also provided with a port 92 which communicates with a discharge pipe 93 which is normally capped by a cap 94. When it is desired to drain the applicator vat 87 and the reservoir 86, the cap 94 is removed. Otherwise the cap 94 remains in place.

As seen in FIG. 4, the tank. member 81 is relatively thick, along its bottom portion, and is provided with a plurality of transversely extending holes which receive the electrical resistance heating elements 95 which are supplied with electricity through cables 96. A thermostatic bulb or sensor 96 is disposed in a hole in member 81, immediately below the central portion of the vat 87 so as to sense the temperature of the glue within the vat and control the energization and de-energization of the elements 95. Thus, the temperature in the glue pot member 81 is maintained at a preset constant.

The cold glue pot 150 is supported on a pair of transverse rods 310 and 311 of the frame 20.

The glue pot member 81 is surrounded by a sheet metal housing 97 which is provided with a top 98, the top 98 extending over the reservoir 86. A thermometer 99, carried by the cover 98, projects into the reservoir 86 so that the temperature of the glue contained in reservoir 86 may be read on the dial of the thermometer. A pair of bolts 100 project through the glue pot member 81 and into nuts 101 which are secured to the housing 97 so as to maintain the housing in place. Handles 102 are provided on opposite sides of the housing 97 so as to permit the glue pot 80 to be lifted out of the machine.

The lower portion of the housing 97 is supported by a sheet metal platform or bottom 105 provided with opposed downwardly extending flanges 106. Between the opposed flanges 106 is a U-shaped conduit box 107, through which the cables 96 lead.

The bottom edges of the flanges 106 are recessed so as to provide a straight edge portion 108 which merges with a concaved portion 109 forming a bar receiving recess for a cross bar supporting member 110 on the frame 20. In the rearward portion of the flange 106 the edge 108 curves downwardly :so as to partially encompass a second cross bar supporting member 111 of the frame 20. A strap 112 extends between the rear lower end portions of the flanges 106 and threadedly receives a set screw 113 which projects beneath a portion of the cross bar 111 so as to removably secure the glue pot 80 on its cross bar supporting members 110 and 111.

Within the applicator vat 87 is a transverse disc carrying shaft which is journalled by the opposed sides of the glue pot member 81, the shaft 120 projecting outwardly of the glue pot 81 on one side and being provided with a sprocket 121 which is driven by a continuous chain 122 from a sprocket 123 of a clutch 124 on a shaft 125. The shaft 125 extends transversely beneath the glue pot 80 and is rotated by a continuous chain 126 leading from a source of power, such as a motor or shaft (not shown) on a machine. The sprocket 121 is disposed between the housing 97 and the glue pot member 81, the housing being provided with a shield 127 on the upper portion of the housing 97.

The shaft 121 carries a plurality of applicator discs, denoted generally by numeral 130 as seen best in FIG. 7. Each disc 130 is split, diametrically, to provide a pair of opposed complimentary disc segments 131 and 132. The disc segment 131 is provided with a mounting block 133 while the disc segment 132 is provided with a mounting block 134, the two blocks encompassing from opposite sides the shaft 120. Each block 133 or 134 is a rectangular member having a hemispherical recess for surrounding one half of the shaft 120, the two blocks being provided with aligned threaded holes through which bolts 135 and 136 project so as to clamp the blocks 133 and 134 together around shaft 120 and, thereby, clamp the disc 130 onto the shaft 120. It will be understood that, upon loosening of the bolts 135 and 136, the disc 130 may be adjusted laterally along shaft 120. If the bolts 135 and 136 are removed, the disc 130 may be removed from the shaft without removing the shaft, itself, from the glue pot member 81. The block 133 is mounted flat against the side surface of disc 131 while the block 134 is mounted flat against the side surface of disc segment 132.

An interrupted or segmented disc 230, seen in FIG. may be substituted for the disc 130, if so desired. This segmented disc 130 has circumferentially spaced teeth 240 for applying the glue and includes a disc segment 231 and a complimentary disc segment 232, abutting each other along a diametrical edge portion 238. Secured to the disc segment 231 is a block 233 and secured to the disc segment 232 is a block 234, the blocks 233 and 234 functioning the same way as the blocks 133 and 134, being held together by bolts 235 and 236.

Preferably the shaft 120 is provided with approximately four of the discs 130 or 230, each disc 130 or 230 being of the same diameter as each other disc 130 or 230. A doctor blade 140 is disposed adjacent the peripheries of the disc 130, as seen in FIG. 4, this doctor blade 140 extending transversely across the peripheries of all discs 130, at a position below the cover 98, as shown in FIG. 4. The doctor blade 140 is carried by a cross bar 141 which also supports the screen member 88. Preferably this screen member 88 is bolted in place by a bolt 142 projecting through the upper portion of the screen member and into the bar 141.

Mounted on the innermost end portion transversely of the housing 97 spaced rearwardly of discs 130 is a severing bar or knife 170, seen in FIG. 4, which breaks or severs any strands of the hot melt glue as the respective cartons 22 pass away from the periphery of the disc 130.

It will be observed that, in the glue pot member 81, adjacent the bottom portion of the screen member 88, there is a transverse upstanding small ridge 143 which prevents trash, which settles in the reservoir 86 from passing into the applicator vat 87.

The glue is normally at a level L such that a lower portion of all discs 130 are submerged in the glue G. The discs 130 are positively and simultaneously rotated in the direction of the arrow 144, in FIG. 4, so that liquid glue G, picked up by the submerged lower periphcries of the discs 130, will be lifted past the doctor blade 140, thereby permitting the doctor blade 140 to remove any excess from the peripheries, prior to the time that they simultaneously engage the lower surfaces of end flaps 21 of the cartons 22 as the discs 130 approach a top dead center position and transfer the strips 401 to the flaps 21.

COLD ADHESIVE APPLICATOR ASSEMBLY Disposed adjacent the hot melt glue pot 80, ie forwardly thereof between the glue pot and the innermost end of the boom 23, is a cold adhesive applicator pot, denoted generally by numeral 150. This pot 150 is simply an upwardly opening vat which contains a glue, usually a water soluble glue which is liquid at room temperature. The pot 150 carries a transverse shaft 320 which, in turn, carries a plurality of discs 330.

As represented schematically in FIG. 3, a supply tank 155 is provided on the side of frame 30 opposite the tank 66 and supplies glue through pipe 156 to the bottom of pot 150.

Each of the discs 330 is identical to the disc 130 and hence no detailed description of the disc 330 is required. The shaft is driven by a sprocket 321 which, in turn, is driven by a continuous chain 323, passing around a sprocket (not shown) on shaft 325. The shaft 325, in turn, is rotated by a sprocket 326, driven by a chain 151 from a sprocket (not shown) on shaft 125.

It will be understood that, when the chain 126 is driven, the shafts and 325 will be driven in unison so that, provided the glue G is in liquid condition, the discs and 330 will be driven at approximately the same peripheral speeds; however, should the glue G be in a solid condition, the clutch 124 which is preferably a ball clutch, will not be engaged, due to the fact that solid glue G will prevent rotation of the disc 130 and retard the initial rotation of shaft 120. When, however, the glue G within the glue pot 80 is in a liquid condition, having been heated by the electrical resistance heating elements 95, the shaft 120 will then not be arrested by discs 130 and will be rotated at approximately the same speed as shaft 320.

OPERATION From the foregoing description the operation of the present device should be apparent. The boxes or cartons 22 being fed inwardly along the boom 23 will pass first over the cold adhesive glue pot 150, whereby strips of cold adhesive will be disposed along the lower end flaps 21 to form cold spaced parallel, liquid adhesive strips 400 (FIGS. 9 and 12). Thence, the carton 22 passes over the hot melt glue pct 80 where its end flaps '21 receive the hot melt strips 401 between the strips 401, as illustrated in FIG. 9.

Since the glue pots 80 and are less wide than the width of the carton 22, the side flaps 25 straddle each glue pot 80 and 150. I

If the discs 230 are employed, an interrupted strip of hot melt 402, seen in FIG. 12, will be provided, corresponding the pattern along the periphery of the discs 230. In other words, each tooth 240, projecting outwardly on the peripheral portion of the disc 230, will apply an increment or a strip portion 402 of hot melt, corresponding to the peripheral length of that tooth 240. The spacing between adjacent segments of the hot melt glue 402 will correspond to the spacing between adjacent teeth 240. Thus, various patterns of hot melt glue may be devised by varying the teeth 240. After passing over the hot melt glue pot 80, the carton 22 or 22a passes inwardly of the machine and the side flaps 25 are folded in conventional fashion against the end flaps 21 and held for a sufficient length of time for the hot melt strips 401 or 402, as the case The advantages of the construction herein described are quite numerous in that the construction of the assembly for applying the hot melt glue is quite simple and yet there is nothing in the structure which will permit the hot melt to clog. Furthermore, the disc 130, rotating in the hot melt glue G will provide circulation for the glue and thereby maintain a uniform viscosity for the hot melt glue. The discs 130 or 230 are adjustable laterally by simply loosening the bolts 135, 136 or 235, 236 as described above. Each disc 130 or 230 may be individually removed and replacedshould there be any need to do so. There is no need for any valves to function in providing a prescribed skip in applying the glue G since, if the periphery of the discs 130 or 230 do not engage a portion of a flap 21, no glue is applied. Hence, there is no wasted glue which may be discharged inadvertently or blown to one side. Furthermore, there is no high pressure applied to the glue and hence there is no tendency of the glue to leak or to be applied inadvertently to any part of the carton or machine.

The clutch 124 is self regulating for temperature in that it is readily apparent visually when the discs 130 begins to rotate that the glue G is at a proper temperature to be applied. The doctor blade 140 may be readily and easily adjusted should there by any need to change the amount of glue G to be applied by the discs 130.

Preferably the hot melt or thermoplastic glue G will be in condition to be applied at about a temperature of 350F and hence the thermostats can be manipulated to maintain such a temperature, even though the temperature of between 275F and about 400F would be suitable. Preferably the discs 130 are arranged, out of longitudinal alignment with the disc 330, and will apply the glue G in longitudinal lines 401 precisely where the glue G is desired. The slotted or interrupted periphery discs 230 will use less glue G and hence provide a suitable seal at less cost than has been achieved heretofore. If a greater number of strips 400, 401 or 402 of glue are desired along the end flaps 21, it is a simple matter to install additional discs 130 or 330.

The addition of glue G is a simple matter, regardless of whether the inverted jug feeder a automatically controls the level of the glue G or whether it is controlled through the addition of glue, as needed, to the tank 66. In any event the level of the hot melt glue G is not critical since the doctor blade 140 will regulate the amount of glue which is applied by the peripheral portions of the discs 130. When the jug feeder 65a is employed, a large amount of cold glue may be added to the premelt tank without chilling the glue in the hot melt pot 80. Furthermore, this will automatically control the level of the glue in both the glue tank 66a and in the glue pot 80a. Indeed, when utilizing either the structure of FIG. 5 or the structure of FIG. 6, it is a simple matter to add an appreciable amount of glue G to the machine from one side while the machine is running. It is also a simple matter in the structure of the present invention to drain the glue from the system.

The parallel pendulum arrangement of the hold down bars 46 and 47 eliminate the necessity of close adjustment of the machine to receive cartons 22 which may vary in dimension. This automatically compensates for normal manufacturing tolerances found in the cartons 22. Furthermore, since the downward force on each carton 22 is approximately the same, a very constant pressure is applied which assures that the lower flaps 21 are level and even for good glue spreading.

I claim:

1. An apparatus for applying glue to cartons, comprising:

a. conveyor means for moving successive righted cartons with their flaps folded inwardly toward each other along a prescribed path;

b. a hot melt glue applicator disposed adjacent and below said path of travel for applying to said flaps of the cartons a thermoplastic glue which is solid at room temperature, said hot melt glue applicator including a glue pot having an upwardly open glue carrying cavity, means for heating said glue pot to maintain the glue in said cavity in a melted and liquid condition, and transversely spaced applicator discs rotatably carried by said pot, said applicator discs being at positions in said pot such that the lower peripheral portions of said discs are normally submerged in the glue carried in said pot, said discs being rotatable and being disposed sufficiently close to said path of travel that the upper peripheries of said discs engage said flaps of said cartons for transferring the glue on the peripheries to said flaps as said flaps are engaged with said upper peripheries of said disc;

c. means for yieldably urging said carton in its movement so as to position said flaps of said carton against the upper periphery of said discs sufficiently to receive the glue from said discs;

d. a supply tank disposed adjacent said conveyor means and into which said thermoplastic glue in a solid condition is charged;

e. a pipe connecting the lower portion of said supply tank to said glue pot;

f. means for heating said supply tank and said pipe for maintaining said thermoplastic glue in a liquid condition in said supply tank and in a liquid condition in said pipe, the means for heating said supply tank and said pipe being sufficient to melt the solid glue in said supply tank without effecting the liquid condition of said glue in said glue pot;

g. the levels of said glue pot and said supply tank being such that said glue, when heated to liquid condition, will flow by gravity through said pipe and into said glue pot to a level determined by the level of liquid in said supply tank.

2. The apparatus defined in claim 1 wherein said hot melt glue applicator includes drive means, a shaft connected to said clutch and journaled by the sides of said glue pot, said shaft being disposed above the normal level of the liquid glue, said discs being connected to said clutch for rotation thereby only when said heating means has heated said glue within said glue pot to a liquid condition.

3. The apparatus defined in claim 1 includes a severing bar, rearwardly adjacent said discs for breaking or severing strands of glue extending from said discs to the flaps of said carton.

4. The apparatus defined in claim 1 wherein said cavity includes a reservoir and an applicator vat disposed in side-by-side relationship, a filter disposed between and separating said reservoir from said applicator vat for filtering the glue as it passes therethrough and means for introducing liquid glue into said reservoir, said discs being disposed over said applicator vat for receiving liquid glue after the same has passed from said reservoir into said vat.

5. The apparatus defined in claim ll including a shaft for rotatably carrying said discs, drive means for rotating saidshaft and a clutch between said means and said shaft, said shaft being journaled by the sides of said glue pot and being disposed above the normal level of the liquid glue therein.

6. The structure defined in claim 1 wherein certain of said discs are circular and have their peripheries notched to provide radially aligned circumferentially spaced teeth with convex concentric surfaces for applying to the flaps of said cartons spaced increments of glue longitudinally along the flap adjacent of said teeth being sufficiently close that the glue is applied as an interrupted strip along said flaps.

7. The apparatus defined in claim 1 wherein said means for heating said pot includes a plurality of spaced heating elements in said pot and a thermostatic control for controlling said heating elements.

8. The apparatus defined in claim 1 including a cold liquid glue applicator disposed adjacent and below said path of travel of said cartons, said cold liquid glue applicator being forwardly of said hot melt glue applicator for applying a glue which is liquid at room temperature to said flaps of said cartons before the carton receives the thermoplastic glue, said cold liquid glue applicator including a second glue pot having an upwardly opening glue carrying cavity, second applicator discs rotatably carried by said second pot at positions in said pot such that the lower peripheries are normally submerged in the glue carried in said glue cavity of said second pot, said second discs being disposed sufiiciently close to said path of travel that the upper peripheries of said second discs engage said flaps of said cartons for transferring the liquid glue on the peripheries of said second discs in longitudinal strips along said flaps as said flaps engage said upper peripheries of said second discs, said first mentioned discs and said second discs having their upper peripheries in a common plane and being so arranged adjacent said path of travel that said first mentioned discs apply their glue between the strips of liquid glue on said flaps.

9. The apparatus defined in claim 8 including means for simultaneously rotating both said first mentioned discs and said second discs at peripheral speeds approximately equal to the linear speed of travel of said cartons.

10. An apparatus for applying glue to cartons comprising:

a. means for moving successive cartons along a pre scribed longitudinal path of travel;

b. means disposed below and adjacent the path of travel for applying glue to the bottom flaps of each carton as it passes said means; and

. hold down means disposed above said path of travel for aligning and holding said successive cartons in said path of travel, said hold down means including a pair of longitudinally extending bars disposed adjacent opposite sides of said path of travel for engagement by the opposite upper edge portions of each carton, means for suspending each of said bars for swinging movement in a longitudinal direction so that the bars will be swung and lifted by the cartons as they move therebeneath and the weight of said bars will be carried by the edges of said cartons, said means for suspending each of said bars including support means and depending links swingably carried by said support means, at least two of said links being connected at longitudinally spaced locations to each of said bars for supporting the associated bar in a pendant and a horizontal position and for holding it in its horizontal position as it is urged by the cartons from its pendant position in an arcuate and upward path.

11. The apparatus defined in claim 10 wherein said support means includes a pair of of brackets for carrying the links of the respective bars, means for moving said brackets toward and away from each other, and means for simultaneously raising and lowering said brackets.

12. An apparatus for applying glue to selected portions of a carton as said carton is passed adjacent the apparatus, comprising:

a. a glue pot having an upwardly opening cavity for containing glue;

b. a shaft carried by said glue pot; and

c. a plurality of discs carried on said shaft, said discs each having opposed separable disc segments on each disc on opposite sides of said shaft and means for clamping said disc segments of each disc in radial alignment on said shaft.

13. The structure defined in claim 12 wherein said means for clamping said disc segments on said shaft includes opposed blocks respectively connected to said disc segments on opposite sides of said shaft and bolt means securing said blocks together.

14. An apparatus for applying glue to selected portions of a carton comprising:

a. a glue pot having an upwardly opening cavity; and

b. a circular disc rotatably carried by said pot for rotation about a transverse axis, said disc being provided along its periphery with radially aligned and circumferentially uniformly and regularly spaced teeth having concentric curved outer surfaces for applying the glue at corresponding longitudinally spaced intervals from said pot in a longitudinal line to said carton as said carton is passed in a longitudinal path adjacent to said glue pot.

15. An apparatus for applying glue to cartons comprising:

a. means for moving successive cartons along a prescribed longitudinal path of travel;

b. means disposedbelow and adjacent the path of travel for applying glue to the bottom flaps of each carton as it passes said means; and

c. hold down means disposed above said path of travel for aligning and holding said successive cartons in said path of travel, said hold down means including a pair of longitudinally extending bars disposed adjacent opposite sides of said path of travel for engagement by the opposite upper edge portions of each carton, means for suspending each of said bars for swinging movement in a longitudinal direction so that the bars will be swung and lifted by the canons as they move therebeneath and the weight of said bars will be carried by the edges of said cartons.

16. In a method of sealing the flaps of fiber board cartons the steps of:

a. disposing the carton with its end flaps folded toward each other on a horizontally disposed boom;

b. yieldably urging said carton toward said boom to maintain said flaps flatter against said boom;

c. moving said carton in a longitudinal path along said boom as said carton is urged toward said boom;

d. engaging the opposite sides of said carton as it is moved along said path and on said boom to hold said carton in a prescribed horizontal position as it is moved further along said path;

e. disposing a pair of glue pots respectively containing liquid glue at room temperature in one pot and heated thermoplastic glue in the other pot in tandem adjacent to the end of said boom;

f. passing said carton as it is held over first said liquid glue in one glue pot and then said heated thermoplastic glue in the other glue pot, with said end flaps of said carton remaining folded toward each other to present a planar surface to said glue pots; and

g. moving both glues in circular paths so that the upper peripheral portions engage transversely spaced portions of said end flaps for applying strips of said glue to said end flaps as said end flaps are carried by said carton along said longitudinal path.

17. The method defined in claim 16 wherein the said circular paths are in vertical planes offset from each other for producing the strips transversely spaced along said end flaps, and folding and holding the side flaps against the surfaces of said end flaps which have received said glue.

18. Method of sealing the flaps of fiber board cartons comprising:

a. disposing a pair of glue pots in tandem;

b. passing a carton in a longitudinal path over first liquid glue in one glue pot and then a hot thermoplastic glue in the other glue pot with the end flaps of said carton folded toward each other to present a planar surface to said glue pots;

c. applying weights to said carton prior to the passage of the carton along said path so as to position the prising:

carton vertically in the path to dispose said end flaps in close proximity to said pots; and

d. moving both glues in circular paths so that the upper peripheral portions engage transversely spaced portions of said flaps for applying strips of said glue to said flaps as said flaps are moved with said carton in said longitudinal path.

19. An apparatus for applying glue to cartons, coma. conveyor means for moving successive cartons along a prescribed path; and

b. a hot melt glue applicator disposed adjacent and below said path of travel for applying to the flaps of the cartons a thermoplastic glue which is solid at room temperature, said [hot melt glue applicator including a glue pot having an upwardly open glue carrying cavity, means for heating said glue pot to maintain the glue in said cavity in a melted and liquid condition, and applicator discs rotatably carried by said pot, said applicator discs being at positions in said pot such that the lower peripheral portions of said discs are normally submerged in the glue carried in said pot, said discs being rotatable and being disposed sufficiently close to said path of travel that the upper peripheries of said discs engage said flaps of said cartons for transferring the glue on the peripheries to said flaps as said flaps are engaged with said peripheries of said discs, said applicator includes a shaft, said discs each includes abutting separable disc segments on opposite sides of said shafts and means for removably joining said disc segments. 

1. An apparatus for applying glue to cartons, comprising: a. conveyor means for moving successive righted cartons with their flaps folded inwardly toward each other along a prescribed path; b. a hot melt glue applicator disposed adjacent and below said path of travel for applying to said flaps of the cartons a thermoplastic glue which is solid at room temperature, said hot melt glue applicator including a glue pot having an upwardly open glue carrying cavity, means for heating said glue pot to maintain the glue in said cavity in a melted and liquid condition, and transversely spaced applicator discs rotatably carried by said pot, said applicator discs being at positions in said pot such that the lower peripheral portions of said discs are normally submerged in the glue carried in said pot, said discs being rotatable and being disposed sufficiently close to said path of travel that the upper peripheries of said discs engage said flaps of said cartons for transferring the glue on the peripheries to said flaps as said flaps are engaged with said upper peripheries of said disc; c. means for yieldably urging said carton in its movement so as to position said flaps of said carton against the upper periphery of said discs sufficiently to receive the glue from said discs; d. a supply tank disposed adjacent said conveyor means and into which said thermoplastic glue in a solid condition is charged; e. a pipe connecting the lower portion of said supply tank to said glue pot; f. means for heating said supply tank and said pipe for maintaining said thermoplastic glue in a liquid condition in said supply tank and in a liquid condition in said pipe, the means for heating said supply tank and said pipe being sufficient to melt the solid glue in said supply tank without effecting the liquid condition of said glue in said glue pot; g. the levels of said glue pot and said supply tank being such that said glue, when heated to liquid condition, will flow by gravity through said pipe and into said glue pot to a level determined by the level of liquid in said supply tank.
 2. The apparatus defined in claim 1 wherein said hot melt glue applicator includes drive means, a shaft connected to said clutch and journaled by the sides of said glue pot, said shaft being disposed above the normal level of the liquid glue, said discs being connected to said clutch for rotation thereby only when said heating means has heated said glue within said glue pot to a liquid condition.
 3. The apparatus defined in claim 1 includes a severing bar, rearwardly adjacent said discs for breaking or severing strands of glue extending from said discs to the flaps of said carton.
 4. The apparatus defined in claim 1 wherein said cavity includes a reservoir and an applicator vat disposed in side-by-side relationship, a filter disposed between and separating said reservoir from said applicator vat for filtering the glue as it passes therethrough and means for intRoducing liquid glue into said reservoir, said discs being disposed over said applicator vat for receiving liquid glue after the same has passed from said reservoir into said vat.
 5. The apparatus defined in claim 1 including a shaft for rotatably carrying said discs, drive means for rotating said shaft and a clutch between said means and said shaft, said shaft being journaled by the sides of said glue pot and being disposed above the normal level of the liquid glue therein.
 6. The structure defined in claim 1 wherein certain of said discs are circular and have their peripheries notched to provide radially aligned circumferentially spaced teeth with convex concentric surfaces for applying to the flaps of said cartons spaced increments of glue longitudinally along the flap adjacent of said teeth being sufficiently close that the glue is applied as an interrupted strip along said flaps.
 7. The apparatus defined in claim 1 wherein said means for heating said pot includes a plurality of spaced heating elements in said pot and a thermostatic control for controlling said heating elements.
 8. The apparatus defined in claim 1 including a cold liquid glue applicator disposed adjacent and below said path of travel of said cartons, said cold liquid glue applicator being forwardly of said hot melt glue applicator for applying a glue which is liquid at room temperature to said flaps of said cartons before the carton receives the thermoplastic glue, said cold liquid glue applicator including a second glue pot having an upwardly opening glue carrying cavity, second applicator discs rotatably carried by said second pot at positions in said pot such that the lower peripheries are normally submerged in the glue carried in said glue cavity of said second pot, said second discs being disposed sufficiently close to said path of travel that the upper peripheries of said second discs engage said flaps of said cartons for transferring the liquid glue on the peripheries of said second discs in longitudinal strips along said flaps as said flaps engage said upper peripheries of said second discs, said first mentioned discs and said second discs having their upper peripheries in a common plane and being so arranged adjacent said path of travel that said first mentioned discs apply their glue between the strips of liquid glue on said flaps.
 9. The apparatus defined in claim 8 including means for simultaneously rotating both said first mentioned discs and said second discs at peripheral speeds approximately equal to the linear speed of travel of said cartons.
 10. An apparatus for applying glue to cartons comprising: a. means for moving successive cartons along a prescribed longitudinal path of travel; b. means disposed below and adjacent the path of travel for applying glue to the bottom flaps of each carton as it passes said means; and c. hold down means disposed above said path of travel for aligning and holding said successive cartons in said path of travel, said hold down means including a pair of longitudinally extending bars disposed adjacent opposite sides of said path of travel for engagement by the opposite upper edge portions of each carton, means for suspending each of said bars for swinging movement in a longitudinal direction so that the bars will be swung and lifted by the cartons as they move therebeneath and the weight of said bars will be carried by the edges of said cartons, said means for suspending each of said bars including support means and depending links swingably carried by said support means, at least two of said links being connected at longitudinally spaced locations to each of said bars for supporting the associated bar in a pendant and a horizontal position and for holding it in its horizontal position as it is urged by the cartons from its pendant position in an arcuate and upward path.
 11. The apparatus defined in claim 10 wherein said support means includes a pair of of brackets for carrying the links of the respective bars, meaNs for moving said brackets toward and away from each other, and means for simultaneously raising and lowering said brackets.
 12. An apparatus for applying glue to selected portions of a carton as said carton is passed adjacent the apparatus, comprising: a. a glue pot having an upwardly opening cavity for containing glue; b. a shaft carried by said glue pot; and c. a plurality of discs carried on said shaft, said discs each having opposed separable disc segments on each disc on opposite sides of said shaft and means for clamping said disc segments of each disc in radial alignment on said shaft.
 13. The structure defined in claim 12 wherein said means for clamping said disc segments on said shaft includes opposed blocks respectively connected to said disc segments on opposite sides of said shaft and bolt means securing said blocks together.
 14. An apparatus for applying glue to selected portions of a carton comprising: a. a glue pot having an upwardly opening cavity; and b. a circular disc rotatably carried by said pot for rotation about a transverse axis, said disc being provided along its periphery with radially aligned and circumferentially uniformly and regularly spaced teeth having concentric curved outer surfaces for applying the glue at corresponding longitudinally spaced intervals from said pot in a longitudinal line to said carton as said carton is passed in a longitudinal path adjacent to said glue pot.
 15. An apparatus for applying glue to cartons comprising: a. means for moving successive cartons along a prescribed longitudinal path of travel; b. means disposed below and adjacent the path of travel for applying glue to the bottom flaps of each carton as it passes said means; and c. hold down means disposed above said path of travel for aligning and holding said successive cartons in said path of travel, said hold down means including a pair of longitudinally extending bars disposed adjacent opposite sides of said path of travel for engagement by the opposite upper edge portions of each carton, means for suspending each of said bars for swinging movement in a longitudinal direction so that the bars will be swung and lifted by the cartons as they move therebeneath and the weight of said bars will be carried by the edges of said cartons.
 16. In a method of sealing the flaps of fiber board cartons the steps of: a. disposing the carton with its end flaps folded toward each other on a horizontally disposed boom; b. yieldably urging said carton toward said boom to maintain said flaps flatter against said boom; c. moving said carton in a longitudinal path along said boom as said carton is urged toward said boom; d. engaging the opposite sides of said carton as it is moved along said path and on said boom to hold said carton in a prescribed horizontal position as it is moved further along said path; e. disposing a pair of glue pots respectively containing liquid glue at room temperature in one pot and heated thermoplastic glue in the other pot in tandem adjacent to the end of said boom; f. passing said carton as it is held over first said liquid glue in one glue pot and then said heated thermoplastic glue in the other glue pot, with said end flaps of said carton remaining folded toward each other to present a planar surface to said glue pots; and g. moving both glues in circular paths so that the upper peripheral portions engage transversely spaced portions of said end flaps for applying strips of said glue to said end flaps as said end flaps are carried by said carton along said longitudinal path.
 17. The method defined in claim 16 wherein the said circular paths are in vertical planes offset from each other for producing the strips transversely spaced along said end flaps, and folding and holding the side flaps against the surfaces of said end flaps which have received said glue.
 18. Method of sealing the flaps of fiber board cartons comprising: a. disposing a pair of gluE pots in tandem; b. passing a carton in a longitudinal path over first liquid glue in one glue pot and then a hot thermoplastic glue in the other glue pot with the end flaps of said carton folded toward each other to present a planar surface to said glue pots; c. applying weights to said carton prior to the passage of the carton along said path so as to position the carton vertically in the path to dispose said end flaps in close proximity to said pots; and d. moving both glues in circular paths so that the upper peripheral portions engage transversely spaced portions of said flaps for applying strips of said glue to said flaps as said flaps are moved with said carton in said longitudinal path.
 19. An apparatus for applying glue to cartons, comprising: a. conveyor means for moving successive cartons along a prescribed path; and b. a hot melt glue applicator disposed adjacent and below said path of travel for applying to the flaps of the cartons a thermoplastic glue which is solid at room temperature, said hot melt glue applicator including a glue pot having an upwardly open glue carrying cavity, means for heating said glue pot to maintain the glue in said cavity in a melted and liquid condition, and applicator discs rotatably carried by said pot, said applicator discs being at positions in said pot such that the lower peripheral portions of said discs are normally submerged in the glue carried in said pot, said discs being rotatable and being disposed sufficiently close to said path of travel that the upper peripheries of said discs engage said flaps of said cartons for transferring the glue on the peripheries to said flaps as said flaps are engaged with said peripheries of said discs, said applicator includes a shaft, said discs each includes abutting separable disc segments on opposite sides of said shafts and means for removably joining said disc segments. 